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Capacitance and DF Measurement of Circuit Breakers
Charging currents are expected to be small. Under dry ambient conditions,
power factor results will be small and dielectric losses close to zero.
Higher than normal UST measurement could be due to a defective vacuum
bottle allowing moisture to enter or surface leakage across the vacuum housing.
Clean the surface of the vacuum bottle and retest. Ensure that all cabinet
heaters are working to maintain a sufficient temperature surrounding the
vacuum bottles.
9.6 Air Magnetic Circuit Breakers
The tests and test modes on air-magnetic circuit breakers are conducted in the
same manner as the vacuum circuit breakers.
9.7 Oil Circuit Reclosers
The testing of oil circuit reclosers is performed in the same manner as the testing
of oil circuit breakers.
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